I'd suggest you look at Stack Overflow engineering posts. Their architecture is about as simple as you can get for a service their size. A bunch of web servers

I'd suggest you look at Stack Overflow engineering posts. Their architecture is about as simple as you can get for a service their size. A bunch of web servers running plain old ASP.NET MVC code (recently upgraded to use ASP.NET Core). A handful of SQL server machines for the database, simple sharding strategies. Some Redis machines for caching.